The polymerization and copolymerization of 1-olefins rapidly and economically with a catalyst was primarily initiated by K. Ziegler who developed two component catalyst systems based on compounds of the Group IV-VIB metals of the periodic table with an organometallic compound of Groups I-IIIA of the periodic table. These catalysts efficiently promoted the polymerization and copolymerization of olefins. Since this discovery, numerous catalysts have been developed as improvements over the original Ziegler catalysts.
Although these later developments based on the original work by Ziegler produced in many instances superior catalysts, none have the improved properties and characteristics achieved with the catalysts of the present invention.
The catalysts of this invention are defined as follows:
A solid catalyst for use with an organometallic cocatalyst in the polymerization and copolymerization of 1-olefins, prepared by reacting:
(A) a support having surface hydroxyl groups and comprising PA0 (B) an organosilicon compound of the formula (R.sub.3 Si).sub.2 NH, where R is a hydrocarbyl group selected from C.sub.1 -C.sub.20 alkyls, aryls, alkaryls or aralkyls or mixtures of these; PA0 (C) a Group IIA organometallic compound or a complex of said Group IIA compound with a Group IIIA organometallic compound; and PA0 (D) a transition metal compound of a Group IVB, Group VB or mixtures of these metals; or PA0 (C') the Group IIA organometallic compound or complex of step (C) is reacted with the product of step (A)(2) prior to the reaction of step (B). PA0 1. Silanated support or dried support followed by excess of the silicon compound, magnesium compound, and titanium compound. PA0 2. Silanated support followed by the magnesium compound, silicon compound, and titanium compound.
(1) silica, alumina or silica-alumina or mixtures of these, or PA1 (2) an organosilane treated support of (A)(1) or mixtures of these;
The catalysts of this invention have very high activity and produce polymers which do not require a catalyst removal step. The catalysts of the invention are free following and produce polymers with good particle nature. The polymers made by using the new catalysts described herein have narrower molecular weight distribution and lower elasticity than polymers produced by prior art catalysts. The specific organic silicon compounds of this invention interact with or on the catalyst active sites and modify the catalyst's electronic structure resulting in the following unusual polymer properties. Polymers with lower elasticity and narrower molecular weight distribution are prepared and can be used to produce high strength objects such as blown films. This is highly important especially in the production of blown films from the ethylene-.alpha.-olefin copolymers currently manufactured under the commonly used term, linear low density polyethylene (LLDPE).
The catalysts also can be used to produce polymers with higher melt index than prior art catalysts. Polymers with high melt index and narrow molecular weight distribution permit the production of exceptionally tough and stiff products with faster production cycle.